Research On The Characteristics Of Photosynthetic Variations Between Three Conifer Species In The East Of The Qilian Mountain

This research made use of portable Li-6400photosynthetic measure system with the open gas exchange system and pocket automatic weather station were carried on the research on3Kind of conifers(Sabina przewalskii, Pinus tabulaeformis. Picea wilsonii), photosynthetic characteristic were measured in the East of the Qilian Mountain.The result showed that:3Kind of conifers photosynthetic rate are all typical one-peak and double-peak curve.In one-peak months, the peak value appears at10:00or12:00; and in double-peak months, the peak in the morning appears at10:00or12:00; the peak value in the afternoon appears at14:00or16:00. The photosynthetic rate of Pinus tabulaeformis and Picea wilsonii have the same diurnal variation.they appear double-peak during the main growth period, and appear one-peak during early and late growing season. The photosynthetic rate of Sabina przewalskii appears one-peak at early growth period,and appears double-peak in other months.3Kind of conifers photosynthetic rate show that S. przewalskii>P. wilsonii>P. tabulaeformis. The seasonal photosynthetic rate of P. wilsonii show:Sep.>Oct.>Aug.>Jul>May.>Jun.>Apr.>Mar. The photosynthetic rate of P. tabulaeformis. Show:Sep.>Aug>Jul.>Oct>May.>Jun.>Apr.>Mar. The seasonal photosynthetic rate of S. przewalskii show that:Sep>Aug>May> Jun.> Jul> Oct.>Apr>Mar. P.tabulaeformis.and S.przewalskii show a highly photosynthetic rate value at May in two years measurement. The reason maybe for the nutrient accumulation of the high growth at June.From the seasonal change of water use effiency (WUE) of3conifers research,we can seen that the WUE of P. wilsonii and P. tabulaeformis. at lower elevation higher than the WUE of S. przewalskii.The water use effiency(WUE) of P. wilsonii shows a "U"type from march to October.P. tabulaeformis.and S. przewalskii.has the same trend change for the water use effiency (WUE).but differ from the peak months.According to carry on the multiple linear regression analysis for the main factor effecting the net photosynthetic rate (Pn),such as Intercellular CO2concentration (Ci), Stomatal conductance (Cond),Temperature (Ta), Air relative humidity (RH), Photosynthetic active radiation (PAR). We found that the photosynthetic rate of3conifer has the same main climate factor and physiological factor, respectively, the Air temperature (Ta) and Stomatal conductance (Cond).After collected the tree ring samples from near the photosynthetic observation points, and analysed the tree-ring width chronologies of3conifers, we can seen that the average width (RW) show P. wilsonii> P. tabulaeformis.>S. przewalskii.Average sensitivity (M.S.),standard deviation (s. d.), t mean correlations among all radii (Rl), mean correlations between trees (R2), mean correlations within the same tree (R3), signal-to-noise ratio (SNR), sample the explanation for the overall signal (EPS), variance in first eigenvector (PCA1)show P.tabulaeformis.>P. wilsonii>S.przewalskii. There areIn the research of tree width and the response of the climate factor study, we found that the standard chronology (STD) of P. wilsonii and P. tabulaeformis. have very consistent response to precipitation at low altitudes. There are significantly positively related to the precipitation of the summer before the year (P6P8) and summer (C6C8).The standard chronology (STD) of S. przewalskii. Has significantly positively relationship with the summer precipitation. Such differences between P. wilsonii and P. tabulaeformis. may be mainly caused by species differences, but the differences between P. wilsonii and S.przewalskii. may be mainly caused by the elevation differences in addition.